Keying system



Jan. 2, 1,940.

A. KAHN KEYING SYSTEM Filed April 19,. 1938 55%. "ESE m W. TA Nw K n m o W u IR A F L Ag atente Jan. 2, 1940 [TED STATES PATENT dio Corporation of America, a corporation of Delaware Application April 19, 1938, Serial No. 202,834

5 Claims.

This application concerns a keying system including means for subtracting from either the marking periods or the spacing periods adjustable amounts to thereby regulate the weight of keying. An object of the invention is to provide means for subtracting from the marking impulses, i. e., adding to the spacing intervals an amount equal to the amount by which themarking impulses may be prolonged at the receiver due to multi-path transmission between the transmitter and receiver, and for adding to the marking impulses, i. e., subtracting from the spacing intervals at predetermined amount. The invention is an improvement over Hansells United States application #168,111 filed October 9, 1937. IIr-the Hansell application provision has been made whereby time may be subtracted from the transmitted marking impulses to thereby compensate for time which may have been added to the marking impulses arriving at the receiver due to multi-path transmission between the transmitter and receiver.

In describing my invention reference will be made to the attached drawingwherein the single figure illustrates schematically a source of reverse impulses, a time control or regulating system, and means for reversing the effect of said system to subtract from the marking or spacing times and for applying the resulting impulses to a positive acting tripping or blocking circuit which in turn controls keying means.

In the drawing the relay 2 diagrammatically illustrating keying means of the automatic type, provides plus and minus pulses in accordance with a perforated tape not shown. The output of the keying means is supplied to the contact 4 of a double-pole double-throw switch S. The switch '8 is for the purpose of reversing the manner in which the elements of the rectifier 6 are connected in the, circuit. When the switch is in position A the circuit operates in a manner similar to the operation of the keying system in Hansells United States application #168,111 filed October 9, 1937. The perforated tape, not shown acting through 4 applies negative and positive current pulses to a condenser C1 through a current limiting and antisparking resistor R1. Condenser 01 may serve as a charge accumulator to permit operation of the system even when the automatictransmitter mechanism supplies only short momentary contacts. Charge from condenser C1 with polarity determined by the last contact made by the transmitter mechanism passes through adjustable resistor R2 to condenser 02. The rate of charging of condenser C2-, is different for pulses from 2 of positive polarity than is the rate of discharging ofCz for pulses of negative action of rectifier 6. When the switch S is in the posi tion A the impulses are applied to the cathode k of 6 and to R2's0 that 6 passes negative pulses as does R2 to discharge condenser C2 at a higher rate than C2 is charged by positive i'mtime required for a dot-cycle is fixed at a, given keying speed the period of marking may be made longer or shorter without affecting this time. With the switch S in the position A as described above the marking impulses are shortened. With the switch S moved in position B the impulses are fed to the anode of the rectifier 6 and the positive impulses are passed by 6 as well as by R2 while the negative impulses are blocked by 6 and passed by' R2 only. Here, the marking times are prolonged at the expense of the spaces and keying is heavier. The nature of the keying can be further adjusted by adjusting R2. Thus, heavy or light keying with controllable heaviness or lightness is obtainable. This is done by reversing the position of the switch S and adjusting the value of resistance R2. When the switch is in position A the signal output of the associated locking unit already lightened by the time subtracting circuit can be made lighter by varying the resistor R2. When the switch is in position B the signal already made heavier by the time adding circuit may be made heavier byyarying R2.

The impulses from the regulating system are supplied to a tripping circuit 8 of the general type disclosed in Finch Patents #1,844,950 and #1,948,103. The control impulses are passed on to an arrangement of the Finch tripping unit coupled to the regulating unit by means of condenser ID. The tripping unit provides a cut-off bias which affects the grids of tubes in a tone keyer 3|] and either permits a tone to be passed on tothe line or cuts this tone off in accordance with the keying input.

The impulses, markings, or spacings shortened as described above,'are applied by condenser I to the control electrode I4 of an electron discharge tube I2, the cathode of which is grounded and thereby connected to the ground connection of the time controi circuit. The anode I6 of I2 is resistively connected to the control grid I8 of tube 20, while the anode 22 of tube 20 is resistively connected to the grid I4 of tube I2. A p0 tentiometer 24 in the output circuit of tube 20 supplies biasing potential to the control grids of a pair of tone keying tubes shown at 30. An impulse on grid I4 is amplified in tube I2, im-

' pressed on the grid I8 of tube 20, and amplified in tube 20 and impressed from the anode 22 thereof to the grid I4 of tube I2 to swing the grid I4 in the same direction, thereby insuring a positive tripping action in 8 to produce at 24 a potential which blocks or unblocks the keying tubes 30. A tone frequency impressed on the grids of the tubes in 30 is passed or cut-off from a line which may extend from the anodes of the tubes in 30 to a transmitter or keyed impulse utilization circuit. Thus, a negative impulse on the grids I4 leaves I2 less conductive so that the current in the anode circuit thereof decreases and the potential on the grid I8 increases or becomes more positive so that a heavy current fiows in the anode circuit of I8, thereby lowering the potential supplied by the anode 22 to the grid I4 of tube I2 to further out off or reduce the current fiow in I2 so that the entire action is accumulated. This heavy flow of current in the anode of tube 20 produces a bias sufficiently negative to cut-ofi the tubes in 30. A positive potential on I4 acts in a reversed sense to cut off the current in 20 so that a mean positive bias is applied to the grids of the tubes in 30 and the same become conductive to pass to the tone current, to the transmitter or utilization circuit for keying purposes. I

The brief description given of this tripping or blocking circuit of the Finch type is believed sufiicient to an understanding thereof by those skilled in the art. For more detailed description of circuits of this nature see Finch Patents #1,844,950 and #1,948,103.

I claim:

1. A keying system including means for subtracting time from the marking impulses or spacing intervals comprising a source of impulses of opposed polarity characteristic of signals, a resistor and a condenser in series energized by said source, a rectifier, a second condenser, a resistor in shunt to said rectifier, a pair of output terminals connected to said second condenser, and a reversing switch and circuits for connecting said first resistor and condenser to said rectifier and second resistor and connecting said rectifier and second resistance to said second condenser and reversing the polarity of said rectifier in said connection.

2. A keying system including means for subtracting time from the marking impulses or spacing intervals comprising a source of impulses of opposed polarity characteristic of signals, a resistor and a condenser in series energized by said impulses from said source, a storing device, a uni-directional device, and switching means and circuits for connecting said unidirectional device with said first condenser and resistance and with said storing device and for reversing the polarity of said uni-directional device in said connection whereby said storing device is charged at a rate depending on the polarity of opposed polarity characteristic of signals, a resistor and a first condenser in series energized by said impulses, a rectifier and a second condenser in series adapted to be connected in shunt to said first resistor and first condenser, a pair of output terminals connected to said shunt circuit, and a reversing switch for connecting said rectifier and second condenser in shunt to said first resistor and first condenser and for reversing said rectifier in said connection.

4. A system as recited in claim 3 wherein a second adjustable resistance is connected in shunt to said rectifier.

5. A system as recited in claim 2 wherein a tripping circuit is connected to said storing device.

ALFRED KAHN. 

